The disclosure of Japanese Patent Application No. 2000-225826 filed on Jul. 26, 2000 and No. 2000-245930 filed on Aug. 14, 2000 including the specification, drawings and abstract are incorporated herein by reference in their entirety.
1. Field of the Invention
The invention relates to an internal combustion engine installed in a vehicle, which has a heat accumulator for accumulating heat temporarily, and sending it to a circulation passage where a heat medium flows, and more particularly, a control apparatus and control method for controlling the heat supply from the heat accumulator to the circulation passage.
2. Description of the Related Art
In general, for an internal combustion engine installed in a vehicle such as automobile, it is undesirable to run the engine in the state where the temperature around a combustion chamber has not attained a predetermined temperature (cold state) because this causes problems such as the fuel which is supplied to the combustion chamber not being sufficiently atomized, deteriorating the exhaust characteristics (emissions) and the fuel consumption performance.
However, in practice, excluding the case of restarting after a temporary engine stop, engines must run in a cold state from the moment of engine start until it is finished warming up each time when the engine first started.
In order to solve these problems, a heat accumulator having a function to accumulate heat generated by the internal combustion engine during running in a predetermined accumulation container, and release this accumulated heat to the engine in a cold state is known.
For example, the heat accumulator for an internal combustion engine described in the Japan Patent Application Laid-Open No. 6-185359 stores some of cooling water heated by the radiation from the engine keeping it hot even after the engine is stopped, and heats the engine early by releasing the stored heated cooling water to the cooling system (cooling passage of the engine) during the next engine start.
However, it was likely that, normally, warm up is not completed to a preferable temperature at the instant of engine start even when hot water circulates through the cooling passage of the engine at the time of engine start, and the engine can not be started in a sufficiently warm state. That is, in some cases, it was impossible to control the working state of the engine conveniently, in relation to the heat supply timing to the engine or, the state after heat supply to the engine.
Not limited to the internal combustion engine provided with a heat accumulator, the same problem occurs also in the other heat receiving objects requiring a certain level of warm up, in other words, heat supply, for securing a preferable working state.
In view of the foregoing situations, the object of the invention is to provide a control apparatus of a heat receiving object for performing optimal heat supply from a heat accumulator to the heat receiving object, based on the working state of the heat receiving object. Another object of the invention is to provide an internal combustion engine with a heat accumulator preferably functioning as such a heat receiving object.
In order to achieve the aforementioned object, an internal combustion engine according to a first aspect of the invention comprises a circulation passage for circulating a heat medium, a heat accumulator for accumulating heat, and a heat supply device for supplying the circulation passage with heat accumulated by the heat accumulator through the heat medium, and starts to supply the circulation passage with heat by the heat supply device at a timing set based on specific timing elements related to engine start, and prior to starting of the engine.
Here, timing elements mean parameters in general concerning a period or time, and for example, start timing, end timing or period of a specific operation, or start timing, end timing or a period of the occurrence of a specific event or the like corresponding thereto.
It is most desirable that the engine starts when a predetermined period has elapsed after the start of heat supply to the internal combustion engine by the heat accumulator, for the optimization of the discharge characteristics and fuel consumption in the initial phase of engine running. And, it is preferable to match this engine start timing with a timing when a necessary and sufficient amount of heat supply to the engine is completed (completion timing of heat supply).
It is possible to match the engine start timing with the completion timing of heat supply by starting the engine after the completion of heat supply taking the aforementioned start timing of heat supply as reference. However, in a case where it is desired to start the engine at an arbitrary timing, it is difficult to decide the aforementioned timing of heat supply retroacting from the timing of engine start.
According to the same constitution, it becomes possible to set a start timing of heat supply retroacting by a proper period from the timing of engine start, even when the engine is started at an arbitrary timing by starting to supply heat taking as reference a specific event occurring necessarily prior to engine start.
As for the timing elements, for example, the following timings can be adopted:
(1) Timing when working release of antitheft device is started.
(2) Timing when the door for getting in and out of a vehicle installed with the engine is opened.
(3) Timing when sitting in the driver""s seat is detected.
(4) Timing when fastening of the seat belt provided with the driver""s seat of the vehicle is detected.
(5) Timing when vehicle break operation is detected.
(6) Timing when clutch operation of the vehicle in which the engine is installed is detected.
(7) Timing when release of a door lock for getting in and out of the vehicle is detected.
By adopting the timings of (1) to (7) as the aforementioned timing elements, these operations are sufficiently high in both necessity prior to the starting of internal combustion engine, and reproducibility of operation timing. Consequently, it is possible to reliably set an appropriate start timing of heat supply each time when the engine is started by deciding the start timing of heat supply based on these operation timings.
In addition, according to a control apparatus of heat supply according to a second aspect of the invention, heat supply to the heat receiving object is performed based on the establishment of predetermined conditions. These conditions are determined based on a specific state related to the starting of the heat receiving object and, at the same time, the supply period of heat to the same heat receiving object is controlled based on the specific state related to the starting of the heat receiving object.
Here, the aforementioned heat receiving object means anything performing any action, and to which heat is supplied. In such a heat receiving object, the state of itself is affected by the degree of heat supply. According to the aforementioned constitution, it becomes possible to set a start timing of heat supply retroacting by a proper period from the starting timing of the heat receiving object, even when the heat receiving object is started at an arbitrary timing, by starting to supply heat taking as a reference, for example a specific event occurring necessarily related to the starting of the heat receiving object.
Here, the heat receiving object may be a motor.
When the heat receiving object is a motor, the working state during the starting can be controlled appropriately for a motor whose working state during its start is variable according to the heat coming in and going out.
An internal combustion engine according to a third aspect of the invention comprises a circulation system for circulating a heat medium, and a heat supply device for supplying the engine with heat accumulated by the heat accumulator through the heat medium circulating in the circulation system, and makes the heat supply device supply a plurality of times the engine with heat, prior to engine start.
Here, in addition to fluid such as gas or liquid, the heat medium includes also media including heat (energy) latently but having practically no substance such as light or electric current. The circulation system for circulating such medium may be a circulation passage for fluid such as, for example, a cooling passage of an internal combustion engine, or an electric passage for electric current. Also, it may be a space for propagating radiation heat.
A plurality of times of heat supply means an aspect wherein increase and decrease (variation) of calorific value supplied by a unit time are repeated discontinuously or continuously. That is, it means both an aspect wherein relatively high calorific value and relatively low calorific value are supplied alternately, and an aspect wherein the heat supply is once suspended after a predetermined amount of heat is supplied, and then the predetermined amount of heat is supplied again.
According to the aforementioned third aspect, the heat supply is performed based on the continuous operation mode of the heat supply device. Consequently, a finite amount of heat stored in the heat accumulator can be used for a longer period than a case where calorific value stored by the heat accumulator is discharged (consumed) continuously. That is, consumption of calorific value stored in the heat accumulator prior to the starting of the engine can be prevented, or the temperature of the engine once elevated can be prevented substantially from dropping again, even when the starting timing is unstable, for example, when the starting timing of the engine is delayed for some reason.
Consequently, heat supply is reliably completed at the time of starting the engine, even when the engine is started at an arbitrary timing.
Here, at least one of the plurality of times of heat supply by the heat supply device may be performed during the starting of the engine. In this case, the heat supply is sustained during the starting initial phase of the engine, allowing to enhance further the discharge characteristics and fuel consumption concerning the starting of the engine.
Moreover, a control apparatus of heat supply system according to a fourth aspect of the invention makes the heat supply system supply the heat receiving object with heat a plurality of times, prior to when the heat receiving object starts operating.
According to the same constitution, for example, the heat supply to a heat receiving object is performed based on a discontinuous operation mode of the heat supply system. Consequently, compared to a case where the calorific value store by the heat supply system is continuously discharged (consumed), heat stored in the heat supply system can be used for a long period of time, even if it is limited.
Therefore, in the case of starting the heat receiving object at an arbitrary timing, the heat supply is completed reliably at the moment of start thereof.
Consequently, regarding the heat supply necessary for the starting of the heat receiving object, desired heat supply timing and heat supply amount required for ensuring an optimal working state are applied reliably.
Also, at least one of the plurality of times of heat supply by the heat supply system may be performed during the operation start of the heat receiving object. In this constitution, heat supply is sustained during the starting initial phase of the heat receiving object, allowing the working state necessary for the starting of the heat receiving object to be ensured more suitably.
Here, the heat receiving object may be a motor, and the working state during the starting can be controlled appropriately for a motor whose working state during its start is variable according to the heat coming in and going out.
Also, the motor may be an internal combustion engine, and the combustion state during the starting can be controlled appropriately for an internal combustion engine whose working state during its start is variable, according to the heat coming in and going out, combustion state depends especially on its working state, and wherein the heat supply to be performed in order to stabilize especially its combustion state is preferably completed prior to starting.
The aspects of the invention are not limited to the aforementioned internal combustion engine for a vehicle and a control apparatus of a heat receiving object. Another aspect of the invention is a control method of, for example, internal combustion engine or heat receiving object.